(a) Field of the Invention
The present invention relates to an automotive CCD camera, and more particularly, to an automotive CCD camera used in a lane drift prevention system that enables yellow lane markers to be precisely detected.
(b) Description of the Related Art
In a charge coupled device (CCD) camera, a thin insulating later (e.g., a silicon oxide layer) is deposited on a surface of a semiconductor element, and a plurality of crystalline silicone electrodes is arranged in a row on the semiconductor element. A light diode is provided adjacent to each electrode. If light contacts the light diodes, the light diodes generate electrons and the electrons move in the area of the semiconductor element. Also, if a voltage pulse is applied in sequence to each of the electrodes, a potential in the semiconductor element is transmitted as with a match-bucket relay. Accordingly, the CCD is able to convert optical image data into electric signals. As a result of this capability, the CCD is used in video cameras, facsimile machines, copiers, etc.
A conventional lane drift prevention system is able to recognize lane markers in the road and warn the driver of any departure from the lane or, as in the case of an intelligent transport system (ITS) or intelligent highway system, automatically control the vehicle so that it is maintained in the lane. A conventional system employing the CCD camera will now be described.
With reference to FIGS. 1 and 2, a CCD camera 1 is provided in a position to enable the collection of images of the road in front of the vehicle. Signals corresponding to the road images are transmitted to an ECU 2 by the CCD camera 1, and the ECU 2 processes the image signals to determine if the vehicle is drifting out of the lane. If it is determined that the vehicle is veering from the lane, the ECU 2 operates a drive control system 3 which controls the vehicle so that it returns to a position between the lane markers.
As shown in FIG. 3, the conventional CCD camera comprises a UV filter 10, a condenser 20 and a CCD cell 30. The images collected by the CCD camera are black and white images. Color images are not collected so that the detection of the lane can be performed at a process speed corresponding to the speed at which the vehicle is travelling.
Since the CCD camera used in lane drift prevention systems collects images of the lane using only light travelling in a straight path, the camera has only a limited ability to recognize yellow lane markers. This is a serious restriction in consideration of the widespread use of yellow lane markers.